Hair drying apparatus

ABSTRACT

A portable hair drying apparatus has a tubular body (60) with an air inlet at one end also containing an electric motor driving impeller (73) and powered by rechargeable cells (74). The air flows over a gas burner assembly (61) fed with gas from a liquid gas container (78) via valve means (69). The container (78) may be recharged through valve (69) or detached at a coupling joint (79) and replaced. The gas burner (61) may comprise a tube surrounded by a catalyst impregnated fibre forming a flameless catalytic gas burner. The gas burner may be separated from direct contact with the air flow by means of a heat pump, one end of which is heated by the burner with the other end being located in the air flow.

This invention relates to a hair drying apparatus and is primarilyconcerned with a portable apparatus which may function independently ofa mains power supply.

Conventional hand held hair dryers, even small size units, require anelectrical power input of some 250 watts or more principally to providesufficient heating of the air flow. Power is also consumed by the airimpeller means which may be a tangential, centrifugal or axial electricfan. It is impractical to obtain this order of electrical power fromstorage batteries.

Hand held dryers achieve the drying effect through air flow to speed-upnatural evaporation and heat to further assist the evaporation process.Practicalities dictate a fiarly narrow range of combination of air flowand heat to obviate damage and prevent discomfort both physical andaural. Relative humidity in the environment of use of the dryer alsoconsiderably effects the drying.

In one aspect this invention seeks to provide a hair-dryer which isportable, operating independently of a fixed power source. In a secondaspect the invention provides an improved hair dryer apparatus,preferably portable, to achieve a better and quicker drying processindependently of atmospheric conditions.

According to this invention there is provided hair drying apparatushaving a body unit, air impelling means to draw air through the bodyfrom an inlet and to expel same through an outlet nozzle, and a heatingmeans disposed within the air flow to heat the air during passage fromthe inlet to the outlet, the body being tubular with the air inlet atone end and the air impelling means located within the body at said end,characterized by the heating means being supplied with heat from a gasburner located within the body and connected by a gas feed duct to a gasreservoir within a hand grip secured to the body, the air outlet nozzlebeing provided at the other end of the body.

The burner may be a flame burning kind or a catalytic combustion devicewhich is flameless. Preferably the burner is screened from the air flowand incorporates a flame detector means operative to shut off the gassupply in the event of flame failure. The burner unit may be positionedwithin the air flow to transfer heat to the air passing thereover or byusing a heat pump as the burner means the burner itself may be remotelylocated out of the air flow, for example in a part of the apparatusintegral with the body unit.

The gas may be contained within a body part, such as the handle, and maybe contained in a removable and replaceable cartridge or a containerrefillable from an external gas bottle.

The gas used preferably will comprise mainly butane stored in liquidform. In one embodiment the gas is acetylene produced preferably by theaction of water on calcium carbide, suitably contained integrally or ata remote location.

The air impelling means may be driven by a turbine supplied withpressure gas or within the gas flow path to the burner, said path beingpreferably heated by the burner to increase the energy in the gas tooperate the turbine.

In order to provide a more time-efficient drying process the inventionalso proposes a hair drying apparatus including a cooling means tocondense moisture from the air drawn in prior to heating. Such anarrangement ensures that the air has a reasonable water absorbingcapacity even under conditions of high humidity. Quicker drying can thusbe produced at lower air temperatures.

The cooling mens may be integrated with the gas burner and may include arefrigerant circuit heated by the gas burner with heat being given up tothe air flow prior to expansion producing the cooling of the intake air.The arrangement may comprise a combined regrigerating means and heatpump. The gas supply may be used as the refrigerant being initiallyheated by the burner to drive the turbine and to give up heat prior tothe heating of the air flow by the burner and the thereafter expand toabsorb heat by cooling the intake air flow, the gas being then fed tothe burner.

By simultaneous use of the gas to heat the air flow and cool same goodefficiency in the overall cycle is obtained, being an open cycle wherethe refrigerant is the gas. A closed cycle using a separate refrigerantcan be used in which case the turbine used for the air flow may drive acompressor. An absorptive (Electruolux) refrigerant system could,however, be used.

The apparatus using the cooling means could be electrically poweredusing electric power means for the refrigerant system and air impellerand gas for the heating.

The gas storage cylinder may be made heatable by the gas burner wherebythe pressure energy in the gas for expansion is increased, in such acase the gas storage cylinder can be made rechargeable from a supplycylinder giving a capacity sufficient for a normal operation.

Embodiments according to this invention are shown by way of examplesonly in the accompanying drawings, wherein:

FIG. 1 shows a side sectional part view of one embodiment,

FIG. 1a shows a detail of an alternative catalytic combustion heatingdevice,

FIG. 2 illustrates a modification,

FIG. 3 shows a second embodiment,

FIG. 4 shows a modification of the embodiment of FIG. 3,

FIG. 5 shows a control circuit diagram, and

FIG. 6 shows a further embodiment.

Referring to FIG. 1 this shows part of a hand held hair dryer comprisinga tubular housing 1 with an air inlet 2, electric air impeller mens 3and a gas burner 4. Heated air is expelled through nozzle outlet 5. Theburner 4 includes a flame shielding plate 6 provided with fins 7 todissipate the heat of combustion and a burner body 7a having furtherfins.

The air inlet to the burner may be positioned such that the forceddraught of the air flow passes therein to provide for combustion of highgas flow rates than would otherwise be possible.

A slide valve and switch or trigger 8 forms a control device whichinitiates flow of gas and operates an igniter preferably an electricalmeans such as a piezo-electric device or hot wire. The gas flow mayinclude a valve only opened when the supply voltage is sufficient tooperate the igniter. A flame or temperature detector may be included tooperate the impeller 3 only when the burner is lit.

The trigger 8 may be a slide or other two way switch serving to open agas valve 8a and close switch 8b to drive the fan by battery 8c. The gasmay be ignited by a separate switch 8d and igniter element 8e.

Alternatively the burner may be of a catalytic or flameless kind asshown in FIG. 1a. This comprises a coiled length of tubing 80 which isperforated and around which is wrapped a catalyst such as asbestos fibre81 dipped in a salt of platinum retained by a fine wire mesh 82 and aninitiator comprising a wire 83 heated by a battery 84. This assembly maybe encased within a heat radiating shroud.

The gas supply may comprise a cartridge C insertable into a handle 9integral with housing 1 or a gas container may be provided in the handlewhich is charged from an external cylinder or refill container, thecharge being sufficient for one normal operation. The handle may alsoinclude a battery, preferably rechargeable nickel cadmium or sealedlead-acid, to drive the impeller 3 and power the igniter and flamesensor circuit.

As an alternative both the gas supply and battery can be housed within aportable carrying case and connected to the dryer by flexible piping andcable preferably integrated into a single pipe. The carrying case maythen include a battery charger.

FIG. 2 shows a modification in which the high pressure gas supply 10feeds a turbine 11 forming also a pressure reducer to drive the impeller3 and thence to the burner 7. The gas used conveniently is a butane orpropane mix, the latter being preferred for the arrangement of FIG. 2 inview of the higher pressure available at normal temperatures. The gasmay however be preheated by passage through the burner assembly and inone arrangement the gas storage cylinder is associated, thermally, withthe burner. The cylinder being charged prior to use and absorbing a partof the burner heat output to drive the turbine.

In a modification applicable to all embodiments described the fan isdriven by a turbine powered from a compressed CO₂ gas cartridge or otherinert propellant compounds such as those used in domestic aerosolsprays.

Expansion through the turbine reduces the gas temperature and heat maybe absorbed from the inlet air flow by fins 12 to lower the dew pointand condense excessive water vapour from the air prior to heating thusgiving an enhanced drying effect.

FIG. 3 shows an embodiment wherein a gas storage cylinder 30 or coil ischarged once or repetitively through valve 31 from a cartridge 32. Thecharge cylinder 30 is thermally associated with a gas burner 32 and thehigh temperture pressurised gas is cooled through a coil 33 whichprecedes the burner in the direction of air flow from impeller 34. Thegas is expanded through a turbine 35 to drive the impeller andthereafter through a coil or finned unit 36 where heat is absorbed fromthe incoming air flow to reduce the dew point and condense out excesswater vapour which is passed to a drain 37.

The expanded gas then passes to the burner. This arrangement providesfor some adjustment in the requirement for high gas pressure energy todrive the turbine which might otherwise provide a gas volume in excessof that needed to heat the air. The refrigeration cycle provides a meansof reducing the effective burner heat output. A separate refrigerantcircuit could be used.

If the gas pressure is sufficiently great then the embodiment of FIG. 4provides for the supply 40 to be fed to the turbine 41 directly to driveimpeller 42 and thence to the absorption coil 43 to effect cooling ofthe incoming air.

A valve will advantageously be included in the gas feed to the gasburner, the valve being thermostatically controlled to reduct the gassupply as the temperature rises. The valve may be manually set toprovide temperature control.

The gas driven turbine for the impeller may be coupled with anelectrical impeller means to provide a constant air flow regardless ofgas flow; the gas driven turbine being assisted by the electric impelleras required.

A logic control diagram for the ignition means is illustrated in FIG. 5,comprising a battery voltage sensor 50 to determine if sufficient poweris available for correct control followed by an ignaition device 51which turns on the gas supply 52 and effects ignition. If no gas flameor combustion is detected at 53 the ignition is reoperated but only Nnumber of times determined by counter 54 after which the gas is shut offat 55 and a no-gas ignition indicator 56 lights. If a flame is detectedthe fan 57 is switched on, if electric, and the speed monitored at 58,in addition the outlet air temperature is monitored at 59, if eitherfalls outside limits the gas is shut off. In the event of flame-cut theigniter may be reoperated or overridden to shut off the gas.

The burner may be arranged so that combustion products do not enter theair flow by provision of ducts or shrouds. Such an arrangement willresult in heat being lost and this is minimised by extracting as muchheat as possible from the combustion gases before exhausting same.

A further embodiment is shown in FIG. 6 of the drawings wherein acylindrical casing 60 has mounted coaxially therein a burner assembly 61comprising a jet 62 with air inlet orifices 63 and a burner head 64. Theburner head is shrouded by a screen 65 incorporating heat radiating finsand the whole burner may further be constructed with a large surfacearea by using fins in order to dissipate heat to the air. Associatedwith the burner is a piezo-electric igniter 66 with a manually operablebutton 67 which may be pressed so as to cause a spark to jump betweenelectrodes 68 and the burner head thus igniting the gas. Gas is fed froma control valve 69 which is iperatively coupled with a capillary 70containing a fluid serving as a temperature sensing means whereby thevalve progressively closes on increasing temperature. The valve 69 alsofunctions to switch the gas on or off through a manual slide switch 71which operates an electrical switch 72 connecting an electrically drivenimpeller 73 to rechargeable batteries 74. In the assembly shown fourbatteries 74 are provided within a base portion 75 integral with thehousing 60. A cover 76 enables the batteries to be removed if necessaryand an electrical connector socket 77 enables them to be recharged froman external unit. Gas supply to the valve 69 is taken from storagecontainer 78 forming the lower part of the handle and this may include arefill valve 79 in its base. By constructing the handle of circular formthe container 78 may be unscrewed at a coupling joint 79 and replacedwhen exhausted rather than being refilled. Alternatively, the container78 may be permanently bonded to the battery compartment 75 to form anintegral rugged assembly.

An alternative or additional temperature control means may be providedcomprising a thermistor mounted closely adjacent the burner andconnected either directly or indirectly through a control means into thefan circuit 73. This thermistor is arranged so that increasingtemperature at the burner decreases its resistance thereby increasingthe speed of the fan 73 and hence the flow rate of the air by whichmeans a substantially constant safe air temperature can be maintainedalbeit with varying rate of air throughput.

A further construction which avoids the flame burner would incorporate acatalytic device as indicated in FIG. 1a, the arrangement otherwis beinggenerally similar to that shown. In this arrangement a hot wire would beused to initiate gas combustion rather than the piezo-electric device66.

We claim:
 1. Hair drying apparatus comprising a tubular body with an airinlet at one end, an electric motor at said end, an air impeller drivenby said motor to draw air in through the air inlet, propel the airthrough the body and out through an outlet nozzle at the other end ofthe body, a heating means disposed within the body between said impellerand said air outlet nozzle, said heating means comprising a gas burnerassembly including a coiled tube positioned within the air-flow, one endof the tube being fed with a combustible gas mixture, the tube havingapertures spaced along its length, a fibrous catalyst material aroundthe outside thereof, a support wire on which said fibrous catalystmaterial is retained, a housing secured to and beneath the body, thehousing containing an electric power source connected through switchmeans to drive said electric motor, a gas flow valve operably coupledwith the switch means and to a trigger mounted on the housing for manualoperation, a pressurised liquid gas container connected with the housingand extending to form therewith a handgrip, a gas refilling valveassembly at the base of said gas container, a gas duct connecting thesaid container with the burner through said gas flow valve, ignitionmeans to initiate combustion of the gases, and a temperature sensingmeans operable to close a valve in the gas feed when the burnertemperature rises above a predetermined maximum.
 2. Apparatus inaccordance with claim 1 wherein the air impelling means throughput iscontrolled by a thermistor connected in the supply to an electric motordriving the impeller, the air flow being increased as the temperature atthe burner rises.